Small diameter catheters, such as diagnostic or therapeutic electrophysiology catheters, may be introduced into a patient's body in order to position a plurality of electrodes and/or sensors distally located on the catheter at a selected internal body location. Generally, such catheters have an elongate shape, terminating in a distal end, and having a size to facilitate introduction into the body, for example, through the cardiovascular system to a selected location within a heart chamber.
To couple electrodes carried on the distal end of the catheter to external circuitry, such as a source of energy and/or a processor for receiving or analyzing data from the electrodes, a plurality of respective electrode wires or leads are provided. The electrode wires are connected to respective electrodes on the distal end of the catheter and extend through a lumen inside the catheter to its proximal end. The electrode wires exiting the proximal end of the catheter are typically attached to external connectors, which are adapted for coupling to external circuitry.
Due to the limited space available within the catheters, the electrode wires are generally substantially smaller in diameter than wire used for standard external electrical cables and connectors. For example, an electrophysiology catheter may carry a significant number of electrode wires (e.g. sixty four) in a single relatively small lumen, wherein a wire diameter as small as between about 36 and about 46 gauge is required to fit the respective electrode wires in the lumen. On the other hand, conventional external cable systems are generally adapted for connecting substantially larger wires, for example 24-28 gauge wire.
Ribbon cables, which carry a plurality of discrete wires in a planar arrangement, are often used to connect a variety of standard electrical or electronic components. Ribbon cables, however, are generally incompatible with the small size and shape of the available wire lumen provided in an electrophysiology catheter.
In addition, insulation displacement connectors are a convenient and inexpensive connector often used to mechanically provide an electrical connection between such ribbon cables and other circuitry. These devices typically include a bank of slots for receiving standard size wires, e.g. 24-28 gauge insulated wires, where an individual wire may be mechanically secured within each slot such that a blade in the slot penetrates the insulation to provide an electrical connection.
Such inexpensive commercially available connectors, however, do not have slots that are capable of securely receiving relatively small size wires, e.g., those between about 36 and about 46 gauge, as may be appropriate for the above-described electrode wires in electrophysiology catheters. Instead, to provide a connection between electrode wires and conventional external circuitry, the small size electrode wires must be individually soldered or otherwise individually connected to conventional large wires or connectors. For example, individual electrode wires may be soldered or crimped to 2 mm diameter pins, or they may be placed into "cups" on a connector, such as a "LEMO" style connector, and soldered or adhered with a conductive epoxy.
In addition to the relatively costly procedure of individually connecting the "smaller" electrode wires to the "larger" ribbon cable wires, because of their relatively small size, the electrode wires are often very fragile and/or prone to fatigue. Consequently, the resulting soldered joints tend to be fragile and vulnerable to breaking during the use of the catheters.
Accordingly, there is a need for an improved method for connecting small gauge electrode wires to standard size wires and/or external circuitry.